1. Field of the Invention
The present invention relates to eyeglasses used for sports, industrial activities, eyesight correction, protection of eyes from the sun, and the like.
2. Description of the Related Art
Conventionally, as the eyeglasses of this type, eyeglasses, for example, as shown in FIGS. 8 and 9 have been available. The eyeglasses shown in FIGS. 8 and 9 are sunglasses, and include a properly curved single lens 11 having flexibility and elasticity. At the upper edges of both-side end parts of the lens 11, a pair of right and left frames 12 are fixed, and each of the frames 12 is mounted with a temple 13. Specifically, threaded holes (not shown) are provided at the upper edges of both-side end parts of the lens 11, and the frames 12 are detachably fixed to the lens 11 by installing and tightening machine screws 14 into the threaded holes (Japanese Patent Laid-Open No. 6-175085).
Furthermore, as the eyeglasses of this type, eyeglasses, for example, as shown in FIGS. 10 and 11 have been available. The eyeglasses shown in FIGS. 10 and 11 are sunglasses, and include a properly curved single lens 21 having flexibility and elasticity, a pair of right and left elastically deformable frames 22 mounted in the side end parts of the lens 21, and a pair of right and left temples 23 mounted to the frames 22. The side end part of the lens 21 serves as a frame fitting part 24, a lens fitting hole 25 is provided in the front part of the frame 22, and the frame fitting part 24 is fitted into the lens fitting hole 25. Thereby, the frame 22 is detachably mounted to the lens 21 (Japanese Patent Application No. 2008-218780).
For the eyeglasses described in Japanese Patent Laid-Open No. 6-175085, the frames 12 are detachably fixed at the upper edges of both-side end parts of the lens 11 by using the machine screws 14. Therefore, the fixation strength is sufficient. However, the eyeglasses of this type have a problem that the assembling thereof requires much time and labor, and although being detachable, the frames cannot be attached and detached easily, so that the exchange of lens is troublesome. Also, the eyeglasses of this type have a problem that if the machine screw 14 is tightened too strongly, a flaw is developed easily on the lens 11.
For the eyeglasses described in Japanese Patent Application No. 2008-218780, in the state in which the frame fitting part 24 of the lens 21 is fitted in the lens fitting hole 25 in the frame 22, a stress caused by this fitting is applied to the whole region of the side end part of the lens 21. Therefore, the eyeglasses of this type have a problem that distortion is produced in the side end part by this stress, and this distortion exerts an adverse influence on the optical performance and strength of the lens 21.